Mayon Volcano, Albay Philippines

Renowned as the "perfect cone" because of its almost symmetrically conical shape, Mayon forms the northern boundary of Legazpi City. Local folklore refers to the volcano as Bulkang Magayon (Filipino: 'Magayon Volcano'), after the legendary heroine Daragang Magayon (Bikol: 'Lady Beautiful').[2]

It is located on the eastern side of Luzon, beside the Philippine Trench which is the convergent boundarywhere the Philippine Sea Plate is driven under the Philippine Mobile Belt. Where a continental plate or belt of continental fragments meets an oceanic plate, the lighter continental material overrides the oceanic plate, forcing it down into the Earth's mantle. Magma, formed where the rock melts, may be forced through weaknesses in the continental crust caused by the collision of the tectonic plates. One such exit point is Mayon.

Like other volcanoes located around the rim of the Pacific Ocean, Mayon is part of the Pacific Ring of Fire.

Mayon Volcano is the Philippines' most active volcano and is considered to be the world's most perfectly formed volcano[3] for its symmetrical cone. It is a basaltic-andesitic volcano.[4] The upper slopes of the volcano are steep averaging 35-40 degrees and are capped by a small summit crater. Its sides are layers of lava and other volcanic material.

Recorded eruptions

Mayon has undergone forty-nine eruptions in recorded history. The first recorded major eruption was in 1616. Its 48th and latest major eruption was a quiet effusion of lava on July 14, 2008 ,[5], which was aggravated when a lahar caused by the rains of Typhoon Durian followed on November 30, 2006. A further summit eruption occurred on August 10, 2008.[6] At present the volcano is weakly erupting and may be building up to a larger hazardous eruption.

The most destructive eruption of Mayon occurred on February 1, 1814. Lava flowed but not as much compared to the 1766 eruption. Instead, the volcano was belching dark ash and eventually bombarding the town with tephra that buried the town of Cagsawa—only the bell tower of the town's church remained above the new surface. Trees were burned; rivers were certainly damaged. Proximate areas were also devastated by the eruption with ash accumulating to 9 m (30 ft) in depth. 2,200 Albay locals perished in what is considered to be the most lethal eruption in Mayon's history.[3]

Mayon Volcano's longest uninterrupted eruption occurred on June 23, 1897 which lasted for seven days of raining fire. Lava once again flowed down to civilization. Seven miles eastward, the village of Bacacay was buried 15 m (49 ft) beneath the lava. In Libon 100 people were declared dead—incinerated by steam and falling debris or hot rocks. Other villages like San Roque, Misericordia and Santo Niño became deathtraps. Ash was carried in black clouds as far as 160 km (100 mi) from the catastrophic event. More than 400 people were killed.[3]

Samuel Kneeland, a professor and a geologist had observed the volcanic activity five months before the eruption. Kneeland was amazed with the beauty of Mayon:

At night the scene was truly magnificent and unique. At the date of my visit the volcano had poured out...a stream of lava on the Legaspi side from the very summit. The viscid mass bubbled quietly but grandly, and overran the border of the crater, descending several hundred feet in a glowing wave, like red-hot iron. Gradually, fading as the upper surface cooled, it changed to a thousand sparkling rills among the crevices, and, as it passed beyond the line of complete vision behind the woods near the base, the fires twinkled like stars, or the scintillions of a dying conflagration. More than half of the mountain height was thus illuminated.[3]

No casualties were recorded from the 1984 eruption after more than 73,000 people were evacuated from the danger zones as recommended by PHIVOLCS scientists.[7]

On August 7, 2006: The Philippine government ordered the evacuation of about 20,000 people living near the volcano, stating that an eruption was feared soon.[8] Volcanologists have detected 21 low-frequencyvolcanic earthquakes since early Sunday morning.[9]

On August 8, 2006: The government expected to move some 34,276 people to 31 state-run shelters and warned that the mountain could explode at any time.[10][11]

On August 9, 2006: Volcanologists warned that Mount Mayon could explode at any time but that the gravitational pull of a full moon could provide the final push. A full moon coincided with at least three of Mayon’s nearly 50 explosions over the last four centuries, including the two most recent in 2000 and 2001. Nearly 40,000 people have been moved from an 8 km (5 mi) danger zone on the southeast flank of the volcano, which has been quaking and spitting plumes of ash since July.[12]

On August 10, 2006: Scientists in the Philippines renewed warnings of a major explosion at the Mount Mayon volcano, describing a sudden period of quiet as "ominous". A drop in gas emissions and earthquakes sparked fears that the crater had plugged itself, increasing the likelihood of an explosive eruption.[13]

On August 11, 2006: Scientists said ground surveys showed Mayon was still "swollen" and registered a high number of volcanic earthquakes, emitted large amounts of sulfur dioxide gas and continued to eject lavadown its slope nearly four weeks after it came to life in a "quiet" eruption on July 14.[14] Phivolcs maintained threat level at Alert Level 4 for the next month because of the continued extrusion of lava, ash explosions, steam and smoke plumes, seismic activity, and threat of further eruption.

On September 11, 2006 Phivolcs downgraded threat level to Alert Level 3. "After the ash explosion of September 1, a general decline in the overall activity of Mayon has been established. The decrease in key parameters such as seismicity, gas (Sulfur Dioxide) emission rates and ground inflation all indicate a waning condition. The slowdown in the eruptive activity is also evident from the decrease in intensity of crater glow and the diminishing volume of lava being extruded from the summit".[15]

On October 3, 2006 Phivolcs downgraded threat level to Alert Level 2. "All monitored key parameters such as earthquake levels, ground deformation and gas outputs further declined. In addition, lava extrusion apparently ceased on October 1, 2006 as reported by Ligñon Hill Observatory. The above observations indicate the absence of an intruding new mass of magma." [16]